Telephone-exchange system.



I B. E. ELEMENT. TELEPHONE EXCHANGE SYSTEM.

APPLICATION rum) rm 2a, was: 1,109,620, Patented 88m 1, 1914.

5 SHEETS-SHEET 1.

E. B. CLEMENT. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED FEB. 2a, 1908.

Patented Sept. 1, 1914.

5 SHBETS SHEET 2 Wit" eons E. E. CLEMENT. TELEPHONE EXCHANGE "SYSTEM.

APPLICATION FILED FEB 26, 1908.

Patented Sept. 1, 1914) 5 SHE-BTS SHEET 3.

B. E. CLEMENT.

TELEPHONE EXCHANGE SYSTEM.

APFLIOATION FILED r33, 26, 1908.

1,109,620. Patented Sept. 1, mm

5 SHEETS-'SHBET 4.

Saw wanton 9% hwooeo E. E. CLEMENT. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED FEB. 26, 1908.

Patented Sept. 1, 1914.

5 SHEETS-SHEET 5.

wit" mam UNITED STATES PATENT oFFroE. Y

EDWARD E. CLEMENT; or" WASHINGTON, DISTRICT or COLUMBIA.

TELEPHONE-EXCHANGE SYSTEMI.

Specification of Letters Patent Application filed February 26, 1908. Serial No. 417,976.

Y To all'wl om it may conceiw."

le it known that I, Eon-nun E, CLEMENT, a citizen of the United States, residing at \Vashiugton, 1n the District of Columbia,

have invented certain new and useful Im-.

provements in Telepho'nelfixchange' Systems, of which the following is a specifi cation, reference being had therein to the accompanying drawing. 1

My invention relates to telephone exchangesystems and it consists of the combi-v nations and "arrangements herein described and claimed.

My invention is particularly applicable to those telephone systems of the so-called full automatic or semi-automatie typcs in which the connectivelinks. consist of trunk cir.- cults prov ded with automatic switches for' interconnecting-said circuits and for com-- pleting the connection with a-wantedsnbscriber. The invention hes in the improvement of the means for selecting and conneet-.

mg a calling line with the first connective trunk or link circuit.

In most of the-devices for a similarpnrpose heretofore patented there are numer ous faults, which in practice interfere with the proper working of 'the system, besides causingoccasional. delay and trouble both to those whose duty it is to keep the apparatus in good order and to the subscribers themselves. Thus in mostofthe systems heretofore proposed, the release of the primary switching mechanism can only be brought about afterthc calling line has been picked up and connected to the first trunk. The selectionv and connection of a calling line is usually accomplished by the mere art of. closinp a line circuit when a subscriber .rcmoves his receiver, Butit may happen that the subscriber will open his line circuit again before the switch has ell'ected the desired connection. In such a case the switch is liable to he stopped at the moment that the line circuit is broken and may be in a position where it is entirely (llSCOlllltW-ttd from any actuating circuit \vhaicv-cr. 7

One object of llly-llH-cnliUli is to provide means whereby the. selector switch may be restored to its original position even if the callingsubscriber should open his linecircult during the operation of connection and before the switch has cometo rest on the terminals of the calling line.

Another object of my invention is to provide means for distributing the incoming calls successively among. the idle trunks, thus distributing the load evenly among. all

-of the operators of the exchange.

The two main features of'my present 'in vent-ion consist in the use of a pilot switch responsive to theclosing of a calling subscribers line-circuit ,-wh1ch,- ins turn, is capable of operat ng one of a group of primary selector switches; and in the employinent of a distributing switch which -worl s n connection with the pilot switch. and

causes the incoming calls '-to.be automatically landed on successive idle trunks. In

order to carry out my presentinveiition I employ; in connection with these switches,

ordinary 'rela 'yslv The pilot switch which forms a distinctive featureof.n1yinvention hasa test wiper 'having'a rotary movement but not a vertical movement. Ithas another wiper having both avertical and a Patented se a. 1, 19.14.

rotary movement to connect with the contacts leading to a calling line. The pilot switch in its movements transmits a, series .of impulses to the selector switch and the two switches step around and up sin'iulta neonsly and come to rest practically at the same time on the contacts leading to the calling line. The manner in which hlllS lS IiCCOli'lpllSllCCl, as well as the mannerin.

Fig. 2- shows part of a censhows part of nector switch circuit.

- the rotary test wiper and test contacts. Fig.

7 is a circuit for a modified form of pilot switch. Fig. 8 is a detail view showing a structural embodiment of the modified form of pilot switch shown diagrammatically in Fig. 7.

- Referring now to Fig. 1, I have shown therein the terminal apparatus of three line circuits leading to the subscribers stations A, A and A This terminal apparatus consists of the cut-off relays N, N and N and'the line relays M, M and M together with the contacts controlled by these relays.

The line relays when actuated are adapted to set in motion a pilot switch P and through the medium of the-switch D to effect the connection of a calling line'with an idle trunk. Y

The primary selector switches S, S, etc, are preferably of the same general type as that shown in my pending application Serial No. 399,284, filed October 26, 1907. A brief description of one of these switches will sufiice.

In general the switch consists of a movable shaft 8 having both a rotary and a vertical movement. The rotary movement is efl'ectedby the magnet R while the vertical movement occurs when the ma net V is energized. The means by whic these two movements is accomplished is fully set forth in the application referred to, and the actuating circuits will be fully traced hereinafter.

The pilot switch P is of somewhat similar construction. The lower wiper 'w is a test wiper and its engagement with the contact 0 causes the switch to stop rotating when it reaches a vertical row of contacts 0' leading t0 the calling line. This switch is illustrated in Figs. 5 and 6. It consists in general of a rectangular frame300 inclosed within which are the operating parts. vertical magnet M", a rotary magnet M and a release magnet R The vertical magnet is provided with a pivoted armature 301 arranged to actuate a pawl 302 for stepping up the shaft 303 by its engagement with cylindricalratchet 304. The rotary magnet M has also a pivoted armature 305, with an extension 306 adapted to. rotate the shaft 303 through the engagement of an actuating pawl 307 with a ratchet 308.- The release magnet R is arranged to effect the restoration of the switch to its normal position by the withdrawal ofthe dog 309 from its engagement with the cylindrical magnet 30a The switch is provided with a contact bank having vertical rows of contacts'adapted to be engaged by a wiper w successively as the Shaft is stepped up. Immediately below the the operator of the These comprise a scribers line (such' as that shown in m bank of contacts engaged by the wiper w is a single row of contacts 0 adapted to be engaged by a wiper w. This wiper is mounted on a sleeve or ring 314. carried by the shaft and splined to the latter. The sleeve is held down upon a bearing ring 315 by means of a spring 316, the latter also serving as a circuit terminal. When the shaft is rotated the sleeve 314 is rotated with it and carries the wiper so around into successive engagement with the test contacts a. When the shaft is raised vertically the sleeve is held down by the spring and the wiper w remains in engagement with the contact on which it last rested before the upward movement of the shaft.

During the rotary and the verticalmovements of the pilot switch, impulses are being sent to the selector switch of the first idle trunk which follows the movement of the pilot switch'and, when the latter stops, the wipers of the selector switch 'rest upon the contacts leading to the calling line. The selection of an idle trunk is accomplished as.

before stated through the medium of the switch D- in the manner hereinafter explained.

The circuits controlled by the various re lays shown in Fig. 1 are clearly indicated in the drawing. These circuits will be fully traced in the explanation of the operation of the system.

In Fig. 2 I have shown the trunk as terminating at a plug P. In this figure are also shown the supervisory lamps L and L and calling lamp L9. The jacks J are for the purpose of eompletin the connection with a wanted subscribers lrne on'the insertion by plug P. T indicates the operators set.

Fig. 3 shows part of the central station automatic connective a paratus, including the operators set T connected to the listening key K, the signal lamp L" and the impulse sending device I.

Referring now to Fig. 4, I have shown therein a first selector switch denoted in general by X, a second selector switch Y, and a' connector switch Z. These switches and their circuits are of the well known Strowger typeand are described as to their mechanism in the patents to Keith and Erickson .Nos. 815,176 and 815,321, March 13, 1900. 'They form no part of the present invention except in so far as they are necessary to ,show a complete operative system. It will be understood that anyothcr switches adapt ed to complete the connection of the trunk circuit shown in Fig. 1 with a called sub- 'be substituted for those herein described, the

particular invention in this case lying in the -means by which a calling line is picked up and connected with the operators trunk cir- I will show in detail how calls may be answered and the connections made from a calling to a called subscriber. Let us assume that the subscriber at station A desires to talk with another subscriber whose number is .2312. \Vhen he takes down his receiver his line circuit 1-2 is closed and the line relay M is actuated, the actuating current being from battery B, through 3, 4, M, 5, 1, through the subscribers telephone, back on line-wire 2 and to ground through the armature 6 of the cut-off relay N. Thereupon the armatures 7, 8 and 9 of the line relay M, pull up. The closing of the contacts 7 and 10 causes the energization of the relay E, the energizing current being from battery, through 3, 4, 7, 10, 11, E, 12, through the closed contacts 13 and 14 to ground. Thereupon the armatures 15, 16 and 17 of the relay E are attracted. The pulling up of the armature 17 of the relay E connects battery with the arm d of the switch D over the following path: battery, 13, 19, 17, 20, 21, 22, 23, 24;, d. The arm d is shown resting on a contact connected with an idle trunk. Only three contacts of this set are shown connected to their respective trunks in order to avoid comlexit of circuits in the figure but it will he un erstood that each one of the contacts is connected with the master relay corresponding to R belonging to its particular trunk. d, (1, (Z is always resting on a contact leading to a relay of an idle trunk and the two sets of arms (I, d, d and (Z 61 and d, are carried by the same shaft and are'arranged one above the other, their respective contacts being similarly arranged. The pulling up of the armature 16 of the-relay E energizes the rotary magnet R of the pilot switch P intermittently, current flowing by the following path: battery B, 18, interrupter I, 25, 16, 2c, :27, 2s, 29, 30, R and ground. The intermittent current due to the interrupter I causes the relay R to rotate the shaft of the pilot switch P one step at each impulse.

We will assume that the station A is one of a group of ten stations each connected to its respective contact in the fourth row and all of. the group having a common connection with the test contact 0 associated with the fourth row. Current having been suplied to the magnet R, the latter will cause the pilot switch I to rotate in the manner described, and when the test wiper w en- Qne of the connected switch armsgages the contact 0, the relay F is energized, breaking the energizing circuit of the magnet R at the contacts 27, 28, thereby stopping the switch at the fourth row. The energizing current of the relay F is from, bat- B, through 3, 4, 9, 31, 32, c, w, 33, F,

ter and ground.

At the same time-that the magnet R is being operated an intermittent current is also being sent through the windin of the rotary magnet R belonging to the first idle trunk. I have assumed that none of the trunks are busy and have therefore shown the small arm (Z of the distributing switch as resting on the first contact leading to the relay R of the trunk circuit 100-101. This relay therefore becomes energized at the first closure of the contacts 17 and 20 which connect battery with the arm d by the path already traced, the remaining portion of the energizing circuit being through the wire 34, relay R and to ground. The energization of the relay R closes the circuit of the magnet K through its armature 35. The energizing circuit of the magnet R may now be traced from the wire 29, from which the intermittent current to the magnet R is supplied, thence by conductor 36, 37, 35, 38, R and ground. The magnet R therefore is actuated simultaneously with the magnet R and causes the rotation of the shaft 8 of the switch S to the fourth row of contacts.

The movement of the armature 27 of the relay F breaks the energizing circuit of the two magnets R and R and completes the circuit of the vertical magnet V of the pilotswitch and the vertical magnet V of the selector switch S. The energizing circuit of the former may be traced tron the contact 27, through 30, 40, a1, 12, V and ground,- and that of the magnet V from the branch wire 42 leading from the wire 41, 13, contact 44 of relay 1F, 45, magnet V and ground. The intcru'iittent current placed on the vertical magnet V of the pilot switch causes the shaft of the latter to be stepped up vertically one step for each impulse, the wiper w of the switch engaging the contacts successively during its movement. At the same time that the magnet V is stepping up the switch I, the magnet V is stepping up the switch S, each movement of the pilot switch being accompanied by a corresponding movement of the selector switch. when the wiper w engages the second contact 2 of the row, the energizing circuit of the relay ll is completed over the following path: battery, 3, 4, 8, 46, 2, 'w', 47, H and ground. The pulling up of the armature 40 the relay H disconnects battery from the' of the multiple conductor 50, contact 10, wiper 110, while the extension 49 of the line- Wire 2 is connected tothe trunk conductor 100 by means of the multiple wire 51, con- 1 tact 1c and wiper l'w'.

VV'hen the wipersfof' the selector switch S come to rest on the terminals of the calling line, the cut-off relay N is energized in series with the sleeve relay R, the energizing current being from battery, through 18, 52, R, 53, 54, 55, trunk c0nductor 100, 1, 1, 51, 49, N and ground. The actuation of the cut-off relay N closes the contacts 5 and 6 upon the extensions 48 and 49 at the same time breaking the circuit of the line relay M. Part of the current through the sleeve relay R flows over the sleeve side 2 of the subscribers line, through his instrument, and back upon the tip side 1, through the extension 48, 50, 1, 1*, 101, 56, 57, 58, tip relay It and to ground. The actuation of the armature 59 of the relay R places current on the relay R the energizing circuit .Jeing from the wire 5:2 connected to battery as already traced, 59, 60, (31, (P, 62, R and ground. The movement of the armature 14 of the relay R actuates the magnet R, current flowing from the commutator I, through 15, 14, 1G, R and ground. At each impulse the magnet R steps the switch 1) around onc step. The first step brings the arms (I and (Z on the contacts leading to the next trunk 102 and 103. If this trunk should happen to be busy its sleeve relay R will be energized and battery current will be supplied to the relay It through the wire 63, and the armature 14 being still up, the magnet itwill be again energized and the switch arms will take another step and continue to step around until the arm I! fails to find a contact connected with battery, 0. until it finds an idle trunk. It will thus be seen that by this method of bringing in the idle trunks the calls are distril'mted evenly among the operators of the. exchange and that no one operator is over-burdened with work while others may be idle.

Having now described the manner in which the iii-coming calls are picked up and put on idle trunks I will show the operation of the release mechanism in case a calling subscriber should hang up his receiver before the pilot and selector switches have to come to rest on the contacts of the calling line. In the ordinary process of calling, this contingency could hardly happen because the selection and connection of a callin line with a trunk takes place very rapid y. It might however hat pen in case a subscriber should accidentally lift the switch-hook for an instant. An inspection of the drawing will show that the pilot switch is provided with a pair of contacts (34, which are kept normally apart by means of an insulating cam (36 at the foot of the shaft. At the first rotary motion of the latter the two contacts 6t, (35 are closed and battery is put upon the C(fllhdkir; 67 of the relay 1* and upon the contact 68 and (59 of the relay H. Vhen therefore these relays pull up they are lockc' through their respective contacts 67 and (25 Let us assume that the subscriber who had closed his line circuit has opened it again before the w per w of the Dl t ml: 1' has come to rest on the co wadii'ig to the calling line. The brcaf: .g: of the line circuit deprives the line rcay M of current, allowing its armat'ures to retract. 'l'he retraction of the armature T breaks the energizing circuit of the relay E, already traced. The retraction of the armature 15 of the relay I completes the energizing circuit of the release magi'iet it which re lcases the switch P and restores it to its normal condition. This circuit may be traced from battery, through the contacts 64, 65, armature 15 of relay E, 70, 71, R and ground.

The restoration of the switch S in case a subscriber hangs up before the wipers come to rest on the contacts leading to the calling line, is accomplished as follows: Near the end of the switch shaft 8 is a collar 72 provided with a. socket 73 arranged t"- receive the bent end of a Contact spri 74. At the first rotary movement: of 't switch the collar 72 exerts a camming ac tiouon the bent portion of the spring and forces the spring 74 into engagement, with the spring 75, the latter being connected to ground through the resistance '70. \Vhcn the subscriber hangs up he dciinergizes the relay E for the reason already explained and the retraction of the armature 17 cuts ofi the energizing circuit of the relay R, which as before stated is through the st itch arm (Z. The retraction of the armature M of the relay R now completes an energizing circuit of the sleeve relay it from battery, through 18, 52, ll, 5;, 5t, 55, trunk condm tor 100, 7 1, 75, 76 and ground. The armature 59 of the relay ll engaging its front contact (10 completes the energizing circuit of the release magnet 1t thro -2 t' armature 77 of the tip relay it, It and ground. This restores the switch to its original position and takes the ground off from the relay R by the opening of the contacts 74. 75. It will be not. .1 that while the switch S is making its rotary movement the actuating circuit of the relay lit;

R will be made through the closed connections 74, 75 in case the calling subscriber hangs up his receiver and the armature 54 of the relay R falls back. When the switch makes its first vertical movement its lower wiper passes over contacts which are grounded through the cut-otl' relays of the respective lines, and if a calling subscriber should then hang up his receiver the relay R would be energized by current through the cut-off relays of the respective lines in stead of through the contacts 74 and which are then open.

After the impulses have all been sent. in

and the calling line has been connected with an idle trunk the relay H is energized and locked in the manner already stated, and the movement of its armature (19 closes the energizing circuit of the release magnet R this circuit being as follows: battery, l8, (ii, (35, T9, (39, St), Tl, R and ground. This restores the pilot switch which drops down and turns back to zero position, opening the contacts (it, 67 in the locking circuits of the relays F and H, restoring them to their normal condition. lhe pilot switch is now ready for any othercall that may come in.

As has been before stated the connection of the trunk 100, 101 with the calling line results in the energization of both the sleeve relay It" and the tip relay R The morement of the armature T7 of the relay lt' prevents the energization of the rclci relay ll. .he tip relay R is now un lci control. of the calling subscriber and is driincrgizcd when he hangs up his receiver.

(,onsidering now the use of the manual connective circuit as illustrated in Fig. 2 it will be obsorded that on the pulling up of the armature S1 of the relay R battery out rent is supplied over the wire 18 and through the armature 81, over conductor 8:2, armature 83 ot' the relay 11 at, U resistance r and ground. The operator observing the lighting of the signal lamp presses her listening key K thereby closing the contacts SIP-86, 8788, and connecting the telephone set T" and at the same time closinn the springs 89 4M), thereby shunting the lamp L and its resistance 1', and causing the current to liow through the conductor 91, relay 11 and ground. The relayflR thereupon pulls up and locks through the armature 83 at the same time cutting off the signal lamp which goes out. The operator having learned the number inserts the plug P'into the jack J and thereupon the relay i" is energized, current flowing from battcry, through 92,- R, 93, 200, 7), j, cut-oft relay N and ground. The pulling up of the armature 94 of the relay R puts current onto the supervisory lamp L, while the ac tuation of the cut-off relay N closes the subscribcrs line circuit onto the extensions lead ing to the jack. The operator now presses her ringing key K, thereby cutting off the plug- 1 from the trunk circuit and connecting the ringing generator G".

When the subscriber answers, the supervisory relay R energized in series with the relay it current flowing through the latter as already traced and over the sleeve side 95 of the subscribers line, through the telephone and back upon the tip side 96 0f the subscribers line and thence by conductor 201 through the relay R and to ground. The actuation of the relay R extinguishes the supervisory lamp L through the pulling upof the armature 97.

After conversation has ended and the calling subscriber hangs up his receiver the tip relay R immediately lets go, the sleeve relay R being still energized in series with the cut-off relay N. The retraction of the armature 77 of the relay R completes the circuit of the release magnet R in the man ner already described which when actuated restores the switch S to its normal position, The breaking of the actuating circuit of the sleeve relay R causes it to fall back thereby restoring this part of the connective circuit to its original condition. The retraction of the armature 98 of the relay R causes the light ing or the supervisory lamp L, the current for the latter being traced from battery, tlllcllgll 92, 94, 99 98, 102, L and ground.

When the called subscriber hangs up his receiver. his line circuit is broken, the relay ll falls, back thereby completing the circuit; of the supervisory lamp L". On observing ilik clearing out signals the operator withdraws the plug P from the jack J. This breaks the actuating circuit of the relay R already traced and it lets go, thereby breaking the supervisory lamp circuits and restoring this part of the connective circuit to its normal condition. It will be noticed that even after the relay ll has become deencrnixed, the lamp L will continue to burn because of current through the wire 99, and the same current controlled by relay R will be communicated to wire 61 and so cause the trunk 100-101 to test busy until the plug l is finally pulled. These provisions are ia'iportant in case the called subscriber leaves his receiver oil.

It will also be understood that the usual means for testing a wanted subscribers line is provided in connection with the operators set "l and the key K.

Referring now to Fig. 3 I have shown therein a lamp signal operated in a similar manner to that already described in connection with Fig. I will now describe the means by which the operator completes the connection between the calling and the called subscriber. In the ligure I have represented the operators sending device diagrammatically at l it is to be understood however that this sending device may be in any form so long as it is capable of sending a prede termined number of impulses over either side of the line.

The number which I have assumed to be wanted by the calling subscriber'is 2312. The operator first sends two impulses over the tip side of the trunk 201. Thes current impulses may be traced from the battery, through 103, K, 201, switch arm :10, 105, relay D, 106, ground. Thereupon the relay D pulls up closing the contacts 107 and 108, and completing the energizing circuit of the vertical magnet V. The energizing circuit of the magnet V is from battery, through 18, 109, 110, V, 111, 112, 113, 107, 10s. The two impulses upon the vertical magnet V causes the shaft S of the switch, together with its wipers to ste up to the second row of contacts connecte with a group of ten trunks leading to second selector switches The operator now sends one impulse over the trunk conductor 200 by pressing the key K This impulse causes the operation of the relay E", current flowing by the following path: battery, 103, K 200, switch arm m 114, E and ground. The pulling up of the armature of the relay E closes the contacts 115, 108, thereby completing the energizing circuit of the relay U, the energizing circuit being from battery, through 18, 109, U 115, 108 and ground. The actuation of the relay U momentarily o ens the contacts 112, 113 and closes the ontac'ts 113, 116. The changing of these contacts 112, 113 and 116 produces no result at present and their use will be explained later. When the switch U retracts, the arms at, m m and w of the side switch are moved to the second contact. The moment the switch arm :0 reaches its second contact, battery current is supplied to the rotary vibrating magnet R", the actuating current being from battery, through 18, 109, 110, 117, R, 118, m" and ground. This magnet continues to vibrate and each time it pulls up it rotates the wipers of the switch one step. The test wiper t of the switch passes over the contacts s successively until it finds an idle trunk. As the wiper t passes over contacts leading to busy trunks the relay U will be energized by current from battery through 18, 109, U 119, :20, release rclay WV", 120, Z 8 and to ground through the corre sponding first selector switch of each busy trunk by way of the multiple terminals corresponding to 8 back through the release relay corresponding to W and to ground, the switch arm corresponding to w of the busy selector switch being of course upon its third contact. It will be observed that this circuit includes the relay U and the test relays W and the corresponding test relay in the busy switch in series. The relay U" being high-wound will operate on this circuit while the other two relays will not.

When an idle trunk is found this test circuit is broken since the wiper t of the first selector switch. is no longer grounded. The energizing circuit therefore of the relay U is broken and when it retracts the arms :17, m W, as of the side switch are moved to their third contact. The movement of the armature w breaks the actuating circuit of the rotary magnet R stopping the wipers t and leading to a second selector. The operator now sends in three impulses over the tip trunk conductor 201 and through the connectcd trunk conductor 203. These three impulses cause the relagv D to pull up three times, actuating current being from battery, to trunk 203, over the path already traced, thence through 121, D 122, and ground.

contacts 123 and 124. This energizes the vertical magnet V the energizing current being from battery B, through 18, 125, 126, V 127, 128, 123, 124 and ground. Theactuation of the vertical relay V causes the switch shaft S to step up to the third row of contacts. The operator now sends in one impulse over the trunk conductors 200 and This impulse operates the relay E through the switch arni y and conductor 129. The pulling up of the armature of the relayli closes the contacts 130 and 124, thus actuating the relay U the energizing currcnt of the latter being from battery, through 18. 125, U 130, 12-1 and ground. The rctraction of the relay U as in the case of the first selector switch X causes a move ment of the arms y, M, y and f to their second positions. This encrgizes the rotary magnet R in precisely the same manner as its corresponding magnet R is energized and the shaft S is now stepped around to pick out an idle trunk leading to the connector switch Z. The test wiper t passes over the contacts a and the relay U is energized until the idle trunk is found, at which time it lets go and moves the side switch arms 7 ;2 3 and y to their third position. The subscriber is now connected to a. trunk leading to a connector switch containing the contacts of the wanted line. The operator now sends one impulse over the trunk conductors 201, 203 and 205. The relay D is operated, the energizing current being from the trunk wire 205 through the relay and by the conductor 131 to ground. The pulling up of the armature of the relay ll closes the contacts 132 and 133 thereby energizing the vertical magnet V the energizing circuit of the latter being from battery, through 18, 134, V 135, switch arm 2, 136, Contact 137, 138, 132. 133 and ground. Thcreupon the wiper is stepped up to the ;first row which contains the terminals of the wanted line. The operator now sends one "impulse o'veethe connected trunks 200, 202

t on the contacts a and s of an idle trunk The pulling up of the relay D closes the 1, wane and 204. This energizes the relay E. This relay thereupon pulls up, the movement of its armature closes the contacts 189, 183 and energizes the relay U in the same manner as heretofore described. On the retraction of this relay the arms 2, 2 a, z are moved to their second positions and the in'oyement of the arms 2 cuts oil the vertical magnet and connects the rotary magnet R. The operator now sends two impulses over the connected trunks 201, 203, 205. This actuates the rotary magnet R which steps the switch shaft S around two steps bringing its wipers t, and t into engagement with the contacts 0 and a leading to the wanted line. The operator now sends a final impulse over the conductors 200, 202, and 204. The relay D is actuated and again closes the actuating circuit of the relay U. It will be remem-v bered that the switch arms 2, 2 2 and 2". are now in their second positions.

The actuation of therelay U closes the springs 140 and 141 and if the called line is busy a test circuit is established as follows: battery I 134, 142, release relay W 143, 144, 141, 140, 145, a, 140, t, 0 and to the multiple terminals of the wanted line. It the wanted subscriber was the calling sub scriber of the now busy line this test circuit thus traced to his multiples would be continued to ground through the tip relay of the first trunk corresponding to the relay R". If the called subscriber was also the called subscriber on the busy line the test circuit would be continued through the contact corresponding to the contact (1 and back upon the tip side of the connector switch and to ground through the relay F,

The energizing circuit of the release relay being thus completed this relay is actuated and the pulling up of its armature 170 grounds the release magnet Y which restores the connector switch to' its original position. The disengagement of the wipers t and t from their contacts 1:. (3 opens the circuits of relays F and G, the latter then falling back, and the former remaining disabled. It should be noted that these two relays constitute the tip and sleeve battery supply relays respectively for the called line, corresponding to the battery supply relays R and R of the calling line. Relay G therefore derives current through the cutofi' relay, but relay F receives no current until the call is answered. The relay 0 is disabled through the opening of the contacts 165, 106 when the shaft reaches its lowest position. This relay becomes energized through the energizing of relay 1* when the called subscriber answers.

The calling subscriber may be informed of the busy condition'of the wanted line by any of the ordinary means. Thus a busy back may be automatically connected to the. line. When the calling subscriber hears 'the busy back he hangs up his receiver thereby deiinergizing the tip relay R of the trunk circuit 100, 101. The retraction of the armature 98 of the relay It puts a simulta 201. This impulse comes from battery B,

through 18, 52, 59, 60, 61, 190, 98, and 102,

to the trunk wire 201 and over the same path to armature 98 and thence by wire 09 to trunk 200. These impulses cause the tip relays I), D and D and the sleeve relays E, E and E to operate simultaneously.

The closing of the contacts 172 and 171 of the relays I) and E respectively causes the energization of the relay W the energizing circuit being from battery through 134, 142,

W 143, 171, 172, 173, s", a, 174, W 175,

Y and ground. The pulling up of the armature 17 6 of the relay W closes the contacts 177 and 178. This causes the actuation of the release magnet Y which restores the switch Y. In a similar manner the energizing circuit of the release relay W is completed from battery, through 18, 125, Y,

179, 150, 181, a, t, 120, VV mand ground. The pulling up of the armature 182 of the relay \V" closes the contacts 183, 184 and causes the actuation of the release magnet Y, the actuating circuit of the latter being traced from battery, through 18, 109, -Y, 185, 184, 183, 186 and ground. The actuation of this magnet restores the switch X to its original condition.

\Ve will assume that the wanted subscrib ors line is not busy. \Vhen the wipers t, tcome into engagement with the contacts a and c the relay G" pulls up in series with the cut-oil relay of the called subscribers lineythe actuating circuit being from battery B, through 18, 147 G trunk conductor 200, contacts 148 and 149 of the ringing relay X, trunk extension 150, a t", c, and through the called subscribers cubofl relay to ground. The pulling up of the called subscribers cut-off relay connects his line with the extensions leading to the contacts 0 and The actuation of the relay G puts battery current on the ringing relay X, the actuating circuit being from battery B, through 18, 147, 151, armature 152, 153, armature 154 of relay 0, 155, X, and through the interrupter I to the ground. Owing to the fact that the interrupter I is in circuit, the relay X pulls up periodically breaking the switch-circuit at the contacts 148, 149 and 156, 157 and connecting the generator G through the tip and sleeve sides of the subscribcrs linecircuit through the closure of the contacts 158 and 159. The ringing of the subscriber's bell takes place therefore by current over one side of the When the line and back upon the other.

ixubscriber answers, the tip relay F is actuover the sleeve side of the subscribers line in the manner already traced, back upon the tip side and through c", t, z, 160, 156, 157, 267, F and ground. This happens of course at an interval when the interrupter has cut all current from the ringing relay X allowing it to fall back and to close the contacts 66, 157. The movement of the armature 161 of the tip relay F closes the energizing circuit of the relay 0 said circuit being from battery through 147, 151, 152, 162, 161, 163, O, 161, through the closed contacts 165 and l66,to ground. It will be noted that the contacts 165 and 166 are closed immediately on the first vertical motion of the shaft S of the connector switch. The actuation of the relay 0 causes the breaking of the actuating circuit of the ringing relay X by the movenwut of the armature 15 i. After the relay '1 has pulled up i is locked the lo king circuit being from battery, through 147, 167, 168, 169. (f), 164., 165, 166 and ground. Roth subscribers are now connected for conversation. The battery supply circuit for the calling subscriber is from battery, through the sleeve relay R, over the trunk 100, the sleeve side of the subscriber's line, through his telephone, back upon the tip side over trunk conductor 101 and to ground through the tip relay R". The battery supply circuit for the called subscriber is from battery, through the sleeve relay G, over the sleeve side of the subscribers circuit, through his telephone, back upon the tip side, and to grouml through the tip relay F \Vhen conversation has ended, the clearing out is accomplished in the system I have used for illustration by the calling subscriber hanging up his receiver. The means by which this is done has already been described in connection with the test circuit of relay W of the connector switch. will be remembered that when the calling subscriber hangs up, the tip relay of the trunk 100, 101, is dencrgized and the retraction of its armature 98 puts a simultaneous impulse on both connected trun s which energizes the tip relay D and the sleeve relay E simultaneously thereby completing the release circuits in'the manner already traced.

It will be understood that the release of the switches could be accomplished by the subscriber'putting an impulse on the connected trur k wires for simultaneously operating the *three pairs of relays w en he hangs up his receiver. In fact it is frequentl done in practice but I have not deem it'necessary to show means fordoing this since the particular invention in the resent application lies in the apparatus '.or,efiecting the connection of a calling line with an idle trunk and the distribution of the incoming calls:

While I have shown my invention as working in conjunction with automatic switches of the Keith and Erickson type heretofore referred to it will be understood that any automatic switch for effecting a completed connection with a wanted subscriber may be used. Thus, one having a rotary movement for picking out a row of contacts and then a vertical movement for selecting a particular contact of the row might be used. I therefore do not wish to limit myself to the specific form herein shown and shall claim broadly the necessary elements of my invention in combination with any automatic means for effecting a completed connection.

Fig. 7 shows a circuit permitting the employment of a modified form of pilot switch. In the pilot switch heretofore described there are 110 bank cont-acts, but since the groups of line relays are connected to the row contacts for rotary testing, it is quite evident that cross groups may be similarly connected to common vertical contacts, if suitable provision is made for preventing confusion between the units contacts in different groups if more than one line is calling at the same time. The simplest embodiment of this idea is to have two ten point switches, such as I have shown in my prior application filed April 20, 1907, Serial No. 369,201, the first acting to select the decimal group of lines in which the calling line is to be found, and the second then starting up to pick out the particular line in the group.

Since each switch has ten contacts, I may divide the lines into double groups of ten, that is to say lines numbered from 1 to 10 should have their local contacts 31 connected in common through the wire 32 to the first contact of what I may call the tens bank. Similarly lines numbered from 11 to 20 should have their local contacts 31 connected through the common wire 32 with the second contact in the tens bank, and so on. This much of the connection is precisely the same as that shown in Fig. 1 with regard to the row contacts. Further than this, however, all the lines having the uni nnnr her 1, i. e., 1, 11, 21, 31, etc., should have their relay contacts 46 connected in common to the first contact in what I may call the units bank of the pilot switch. Similarly, all the lines having the unit number 2, i. e., 2,'12, 22, 32, etc.', should have their contacts 46 connected through a common wire to the second contact in the units bank, and so on. The result of this cross combination is that if any particular line is calling it will close its relay contacts onto the common tens and common units contact corresponding to the two digits in its number. For example assume that line No. 46 to be the calling line, and it will be plain that its contacts will close onto the wires leading to the 4th tens contact, and the 6th units contact. The operation of the pilot switch is: precisely the same as that of the switch P prevent interference between lines calling at the same time, I make the tens contacts in pairs, as shown in Fig. 7 so that the battery supply for the units contacts will be fed back through the duplicate tens contacts,

and thus only that unit will be selected which is energized in the group to which the tens contact already selected belongs. For example, let us suppose that lines 28 and 46 are calling. Without any special provision being made, and using the two ten point switches referred to, the operation would be as follows: The relay E would pull up, the switch P would start up, and come to rest with its wiper on the second contact, this being the lowest number calling. The units switch P would then start up and come to rest with its wiper on the 6th contact, this being the first one reached that has battery on it. The result of these conjoined actions is to step up the first idle connector switch S, etc, to the line No. 26 which is obviousl neither of those calling. On the other han using the twin contacts, this confusion cannot occur, for suppose the same numbers are calling, and the tens wiper has moved around to the second contact. Battery current is then fed back over the duplicate contact to the armature contact 8 of the line relay of. line No. 28, ani from thence through the common wire to the No. 8 units contact. The units switch P starts up and goes around until it reaches the 8th contact, this being the first contact that has battery connected to it. Obviously all the other contacts are dead because only the group of lines numbered from 21 to 30 has battery connected to its line relay contacts 8 long as the tens wiper is resting on the second bank contact. Of course, if there are two or more lines in the same decimal group calling at once, then the line having the lowest number will be picked out first, as for example the numbers 24 and 28, or numhers (i2 and (35, or the like.

In practice I prefer to make the two ten point switches I and I in a single or common unit, which as shown in Fig. 8 may be described as follows: A base plate carries the tens and units bank contacts and the duplicate tens contacts arranged substantially in the same manner as in my prior apilication above mentioned in Figs. 5, 6 am 7 thereof. The spindle of the switch extends through the supporting plate, and above the plate a short sleeve is mounted upon it, this sleeve carrying the tens wiper and its twin which cooperates with the duplicate tens contacts. The sleeve also carries its own ratchet wheel and is turned on the spindle by means of the rotary magnet R the same as in Fig. 1 hereof. The spindle has its ratchet wheel below the mounting plate and its operating magnet V secured below the plate. The sleeve and the spindle each of them has its own little spiral retractingspring and both the ratchet wheels of sleeve and spindle are engaged by a pivoted detent or dog controlled by a single release magnet mounted on one face of the plate. This magnet is the same as R in Fig. 1 hereof.

It willbe observed that this modified form of switch is merely a duplication of the ten point switch shown in my prior application and as to its general features is well known in the prior art. This combination form, however, I consider to be original with me and shall therefore claim the same both as to its circuit connections and mechanical arrangement thereof. I am aware that many changes and modifications may be made in the circuits and 'apparatus hereinbefore described without departing from the spirit of my invention which may be stated in broad terms as follows: A pilot switch responding immediately to any calling line in a group to which it is assigned, testing the lines to ascertain which one is calling, and at the same time carrying along with it an idle connector switch, which it leaves in connection with the calling line and then restores itself ready for another call. This arrangement obviously leaves the primary connector switches free from any testing operation. and makes them merely driven switches, positive in their action and in most respects uniform with the ordinary and regular connector switches of the automatic set.

In this system it should be noted that all multipling of the test contacts is done away With and in the special arrangement shown in Fig. 7 even the single set of t sting con tacts is reduced from IlO down to it). so that the connections and cabling represent probably the acme of simplicity in this class of work. In some installations it may prove advisable to have the pilot switch in duplicate for each group of trunks and the lines served thereby, each switch having access to the entire group of lines but controlling only one-half of the group of trunks, so that in case of a breakdown in one pilot switch, the other group of trunks would not be disabled; but ordinarily this would.probably not be necessary.

I contemplate applying this principle of a pilot switch governing concurrently acting connector switches to other purposes than primary selection alone, for example in a number of prior applications I have described and illustrated secondary selector outfits for connecting an idle operators set to the trunk which in turn has become eonnccted to a calling suhseribers line. Among these applications a re serial No. 3G9,20l,filed April 20, 3907; bcrial No. 370,051, tiled April :24, 1907; ,Serial No, 385,874, filed July L3, 190?: Serial No. 366,819, filed April 6, 190T; and Serial No. 383,875, filed July 15, M07. In order to use the pilot switch principle in such secondary selection it is only necessary to follow the circuits of Fig. 1, regarding the line relay M therein as a trunk relay which becomes active when the trunk is in senice, such as R or R and regarding the link circuits link-101, etc, as operators circuits, the operators then being connected substantially as shown in Figs. 2 and 3, but without any plug 1 or extension wires 2002()l. It is believed that this and other methods of applying the principle I have described. will be sulliciently apparent to those skilled in the art without further de scription or illustration, and it is to be 111! derslood that all nonessential variations as well as the al atmlications of my in vention to dlfliWlll contemplate-f i l y claims aleplwnc han i system, a plurality of suhscrnnrs lines, ink circuits for interconnecting id lines, meansv or connecting a tailing line with any link, and a unitary automatic pilot. or selector for said means, ccznmon to a plurality of lines and links, c ntaining: testing terminals for the lines, and acting in response to a call over any line to automatically select said line and SYIlClllOllilllily actuate connecting means to select the same line and C-Jtlllfit't it with an idle link,

In :1 leleplzme exchange system, a plurality of snbstrlbczs" l nes, link circuits for interconnecting said lines, a. plurality of automatic means for connecting callinglines with the links, means for distributing the calls among the links, and a unitary ant-imatie pilot or selector common to plurality of lines and links, containing testing" termi nals for the lines, and a titg rer must; to a call oxxer any line to antoinaticall;v select said line and synchronously actual, i connect ing means to select the ma: line and connect it with an idle link.

3v In a telephone exchange system, a. plnrali of subscribers lines, link circuits for interconnecting said lines, a plurality of antomatic connective devices, a unitary pilot switch arranged. to select a calling line and means associated with said pilot switch for.

efiecting synchronously withthe selection of the calling line the connection of a calling "LHilh among the i and a unitary pilot switch common to a plu-.'

rality of said lines and links containing line testing terminals and adapted in response to a call over any line to test said terminals until the calling line is found, and to synchronously actuate an idle one of said automatic connective means.

In a telephone exchange system, a plurality of subscribers lines, a plurality of link circuits for interconnecting said lines, a unitary pilot switch common to said links and arranged to select a calling line, an automatic switch associated with each link and synchronously controlled by said pilot switch for connecting a calling line with a link and means for distributing the calls among the idle links.

6. In a telephone exchange system, a plurality of subscribers lines, link circuits for in erconnecting said lines, a unitary line seccting pilot switch for selecting a. calling union if: said links, an automatic =ciiictor switch arranged to be syn with each link, a distribtor distributing calls among the idle l n and means controlled by a calling sol: nor for restoring all of said pi ot and primary searches their normal tiling; s

. a a telephone exchange system, a plu i'ality oi subscrihers lines, link circuits for iliter-connecting said lines, a unitary line so looting eleetro-n'lag rnetically actuated pilot snitch common to said lines and links, an clcctro-magnetieally actuated automatic primary selector snitch associated with each link, a. distributim switch for distributing e l l 'ith circuit connections for the pilot switch controlled over the subscribers lines in calling and actuat inncircuit connections for the primary so lector switches controlled by the pilot switch as determim-d by the distributing in a telephone 7ljll,:!i1l9 sy=tem,'a pluo, link circuits for unitary line so h 7 out h conunon to said lines a link circuits, an automatic primary lm tor snitch associated with each link cisi means for causing the pilot switch to a calling line and means associated witch for causing simultaling movements of the :ciated with an idle link a connection with the alitt, of so and with and by said pilot ltli 9. In a telephone exchange system, a plurality of line circuits, link circuits for interconnecting the same, a two-motion primary selector switch associated with each link circuit and containing rows of terminals for the line talking circuits only, a twomotionpilot switch common to a plurality of the primary selector switches, containing rows of individual line testing terminals and an additional testing terminal for each row. actuating means for said pilot switch controlled by any line in calling, means also controlled by a line in calling for changing, the condition of its individual terminal and also of its row terminal in the pilot switch, and actuating means for the primary sclector switches controlled in the movement of the pilot switch, whereby in response to a call the pilot switch will select the row and also the individual contact of the line call ing, and will svnchronously actuate a primary selector switch to select the talking terminals of the same line and connect them to its associated link circuit.

10. In a telephone exchange system, a plurality of subscribers lines, link circuits for interconnecting said lines, means for connecting a calling line with any link, and a unitary automatic calling line pilot selector for said means common to a plurality of said lines and links containing testing terminals for the lines, and acting in response to a call over any line to autonnitically select said calling line and causing simultaneous selective actuation of said connecting means to connect the same calling line with an idle link.

ll. In a telephone exchange system, a plu rality of line circuits to be individually tested for a certain line condition, and a unitary two-motion testing switch responsive to said line condition and to which said lines are connected in groups, said switch being adapted by one. motion to find the group to which a. given line bcl ngiw, and by another i'notion to lind the given line and separate connecting means crmtrolled by said twomotion testing switch for ctlecting QUINN-(F tion with a found line having a given condition.

12. In a telephone exchange system, a plurality of line circuits to be individually test ed for a certain line condition. a two-motion testing switch having certain contacts con mon to certain groups of said lines, and having also an individual contact for each line, and actuating means for said switch controlled by the condition of the lines for actuating aid switch first to move over the group contacts by one motion to find the group of a line, and then to move over the individual contacts to find the individual contact of a particular line of the found group and separate connecting means controlled by said two-motion testing switch for effecting connection with :1 found line having a. given condition.

13. In a telephone exchange systenn a plurality of line circuits to be individually tcsted for a. certain condition, a two-motion testing switch having certain contacts common to certain groups of said lines, and an individual contact for each line the individual contacts of each group and, the group contact being arranged in a vertical row, and actuating n'icans for said switch controlled by the condition of the lines for actuating said switch first to test from row to row on the group contacts to find the group of a line, and thereafter to move over the individual contacts of the row found to find the indii idual line having the condition to which the switch is responsive and step by step connecting means controlled by said two-inotion testinp switch for eli'ecting con nection with a found line having a given condition.

14c .In a telephone exchange system, a plurality of line circuits, link circuits for interconnecting the same, a two-motion primary selector switch associated with each line circuit and containing rows of line talking circuit contacts only. a two-motion calling line selector pilot switch common to a plurality of primary selectors and containing rows of individual calline' line testing terminals, and an additional testing terminal for each row the rows of each said twomotion switches being vertically arranged in horizontal aliuenient on arcs of circles, a wiper for each of said switches adapted tor both rotary and vertical step by step lZUYtlIlGllt, actuating means for said pilot switch controlled by any line in calling;- for causi'ii the wiper of said pilot switch first to rotate over the row testing terminals of the rows to select the row of the calling line, means also control l by line in calling for slim-flo cessati n oi i rotary movement uprn the findingot a row and causing a vertical movementon the row found means also controilcd by a calling line for stom'iing the vertical moycnicnt upon the finding; oi. the ind vidual calling line contact of the row, actuating mean; for the primary selector switches controlled in the movement of the pilot switch, whereby the primary selector switches are actuated each to connect with its link the calling line found by the pilot switch, and means effecting the return of the pilot switch to normal after each finding.

15. in a telephone exchange system. a plurality of subscribers lines divided into groups, group and individual test circuits associated with said. groups and lines respectively link circuits for interconnecting said lines, connective means associated with each link containing terminals of line circuits only and operated by impulses to connect therewith, and group and individual impulse controlling means common to a plurality of said connecting means and operating in said test circuits during the actuation of said connective means.

16. In a telephone exchange system, a plurality of subscribers lines, test circuits for said lines, link circuits for interconnecting the same, connective means associated with each link containing terminals of line circuits only and separate self-contained unitary testing means for said connective means common to a plurality of the same containing terminals of the test circuits only and adapted to test each line upon the connection of said connective means therewith.

In testimony whereof I affix my signature in presence of two witnesses. v

. EDWARD E. CLEMENT. \Vitnesses:

LESTER A. STANLEY, H. F.L6WENSTEIN. 

